1. Field of the Invention
The present invention relates to a stain repellent finish which protects a polyamide substrate from staining. More particularly, the present invention relates to a method for protecting a polyamide substrate, such as nylon, from anionic stains, which method involves applying polysiloxanes having carboxy, phosphonic, or carboxy and sulfonate functional groups to impart repellency to anionic stains.
2. Prior Art
In general, three basic types of organic antistain finishes are known in the art. The first type is an aqueous solution of condensates of formaldehyde with phenolsulfonic acids, napthosulfonic acids, and sulfonates of dihydroxydiphenylsulphones of low molecular weight ranging from about 250 to 700. These organic antistain finishes also known as "sulfonated novolak resins" are described in U.S. Pat. Nos. 4,501,591 and 4,680,212. However, these finishes have a tendency themselves to yellow, and, hence, to discolor a textile substrate such as a carpet.
A second type of organic antistain finish is represented by an aqueous solution of a sulfonated aromatic polymer or copolymer, such as a copolymer of maleic anhydride and an ethylenically unsaturated monomer, such as styrene, subsequently sulfonated to impart stain resistance to carpet and upholstery. Included in this second type is a physical blend of sulfonated novolak resin and a polymer of methacrylic acid. When a physical blend is employed the individual components are applied successively or together in an aqueous treating solution. This second type of organic antistain finish is disclosed in U.S. Pat. Nos. 5,001,004; 4,822,373; and 4,925,707. As a mixture of an aromatic and aliphatic components, this second type of antistain suffers less yellowing than the first type of antistain which primarily consists of aromatic components.
A third type of organic antistain finish known in the art is represented by aqueous solutions of polymers of methacrylic acid and copolymers of polymethacrylic acid free of aromatic components. Examples of such antistains are described in U.S. Pat. No. 4,937,123.
There is an on-going need for an antistain finish or treatment for polyamide substrates, such as nylon carpet and upholstery.
Silicones are not known to be used as antistain finishes for polyamide substrates. Although anionic silicone copolymers are employed in personal care applications such as in U.S. Pat. No. 4,717,498 and as emulsifiers and foaming agents in U.S. Pat. No. 4,777,277, they have not been recognized as effective antistain finishes for a polyamide substrate.